Spring biased rotatable seat pedestal



Sept. 25, 1962 R. H. SAVAGE SPRING BIASED ROTATABLE SEAT PEDESTAL Filed Dec. 9, 1958 Tia. E

R m N w m Unite This invention relates to swivel chairs and particularly to swivel bearing mechanisms for such chairs.

An object of the invention is to provide an improved swivel bearing mechanism for use in a chair of the type described and claimed in the application of Eero Saarinen, Serial No. 648,804, filed March 27, 1957, now Patent No. 2,939,517.

A further object of the invention is to provide a swivel mechanism in which the bearing parts are simplified as compared to the bearings of the prior art.

Another object is to provide an improved bearing mechanism suitable for use with a chair which is supported on a single central column having a relatively narrow neck portion in the middle of the column and an outwardly flaring upper end portion.

A further object is to provide such a bearing structure in which radially acting forces are transferred between the chair and the column by radial bearing structures at the top of the column, and vertically acting thrust forces are transferred from the chair to the column by thrust bearing structures at the neck of the column.

Another object is to provide a swivel chair having a centering spring mechanism for biasing it to a selected angular position with respect to the base.

The foregoing objects are attained in the chair and swivel mechanism described herein, wherein the chair seat comprises a thin shell having a flat undersurface portion at its center. A rotatable, generally cup-shaped radial bearing member has a flange abutting against this flat under surface, and is fastened at its bottom end to the upper end of a vertical tube or shaft extending downwardly and having its lower end abutting against the shoulder of a rotatable thrust bearing member. The two rotatable bearing members and the tube are held together as a unit with the chair shell by means of a through bolt and spring washer. A fixed radial bearing member in the form of a cylindrical sleeve, is attached to the upper end of the column and cooperates with the rotatable radial bearing member. The fixed thrust bearing member, cooperating with the rotatable thrust bearing member, is a block fastened by means of a screw to the neck of the column.

The top of the column and the rotatable bearing member are provided with radially spaced vertically extending lugs. A double coil spring encircles the radial bearing members and has crossed end portions yieldably engaging the opposite sides of the lugs and tending to hold the lugs in alignment, and thereby maintaining the chair in a predetermined angular position.

Other objects and advantages of the invention will become apparent from a consideration of the following specification and claims taken together with the accompanying drawing.

In the drawing:

FIG. 1 is a perspective view of a swivel chair to which the invention may be applied;

FIG. 2 is a fragmentary sectional view, taken on a full size scale, through the axis of rotation of the swivel chair of FIG. 1, showing the upper end of the supporting column and the associated bearing structures; and

FIG. 3 is a cross-sectional view taken on the line III III of FIG. 2, and a smaller scale, showing the center.- ing spring structure.

States Patent Ofliice 3,055,628 Patented Sept. 25, 1962 The chair of FIG. 1, as described in detail and claimed in the copending application of Eero Saarinen, Serial No. 648,804, identified above, comprises a base 1 and a seat-and-back unit '2. Both the base 1 and the seat unit 2 may be molded of plastic and are for the most part, thin-walled hollow shells. A cushion 3 fits into the bottom of the shell 2 so as to provide a comfortable seating surface.

As best seen in FIG. 2, the base 1 comprises a central neck portion 1a and flares upwardly and outwardly from the neck portion 1a to a top portion 1b. The underside of the seat-and-back unit 2 comprises a circular plane portion 2a aligned with the upper end of the top portion 1b of the column. Preferably the outer edge of the upper extremity of the column is provided with a conical surface 1c which faces a formed on the under side of the shell 2.

A rotatable radial bearing member 4 has a generally cup-shaped central portion and a wide horizontal flange 4a extending outwardly from the upper edge of the cup. The bearing member 4 has an aperture 4b formed at its bottom with a downwwardly turned flange 4c encircling the aperture. The horizontal upper surface of flange 4a and the horizontal bottom surface of the bearing member 45, adjacent and encircling the flange 40, must be made flat and parallel.

A tube 5 functions as a shaft and has its upper end fastened, e.g., by welding or silver soldering to the bearing member 4 just outside the flange 4c. The lower end of tube 5 abuts against a rotatable thrust bearing member 6 at a horizontal shoulder 6a.

The flange 4a abuts against the flat portion 2a of the shell 2. A through bolt 7 is threaded at is lower end into the rotatable thrust bearing member 6 and is provided at its upper end with threads to receive the hollow shank of a head member '8 having a laterally extending flange 8a on its upper end. A spring washer 9 having an upwardly convex central portion has its periphery abutting the upper surface of the flat portion 2a of the shell 2. The spring washer 9 and the flat portion 2a are provided with centrally aligned apertures to receive the upper end of the through bolt 7 and the head mem ber 8. The flange 8a is fastened, as by welding, to the upper side of the spring washer 9' and holds the washer resiliently against the bottom of the shell 2. The through bolt 7 holds the shell 2, the washer 9, the radial bearing member 4, the tube 5 and the thrust bearing member 6 together as a unitary assembly.

The rotatable radial bearing member 4 has a peripheral surface machined perpendicular to the flat horizontal surfaces and cooperating with a stationary radial bearing member 10, which has the form of a vertical cylindrical sleeve with an outwardly projectng horizontal flange 10a at its lower end. The periphery of flange 10a is fixed, preferably with adhesive, against a shoulder 1d formed on the inner surface of the column 1.

The under surface of the rotatable thrust bearing member 6 cooperates with a fixed thrust bearing member 11 comprising a block having a tapering under-surface abutting against a conforming tapering surface surface formed in the neck portion 1a of the pedestal. A screw 12 extends through an aperture in the portion 1a and threadedly engages a central opening in the block 11. If desired, a lubricating washer 20 which may be porous metal and impregnated with oil, is provided between the opposing surfaces of the thrust bearing members 6 and 11. The thrust bearing member 11 is provided at its upper end with a projecting cylindrical wall 11a bent over at its upper edge as shown at 11b to enter a recess 6b formed in the rotatable thrust bearing member 6 so as to prevent separation of the parts by lifting of the chair by its seat 2.

The column :1 is provided near its upper end with an similar conical surface 2b inwardly projecting lug 13, which may be molded integrally. The rotatable radial bearing member 4 is provided with a downwardly projecting lug 14. A double coil helical spring 15 encircles the bearing members 4 and 10 and has crossed end portions 15a, 15b, which extend radially outwardly from the coils of the spring 15 and lie on opposite sides of the aligned lugs 13 and 14, as best seen in FIG. 3. In the position shown in FIG. 3, the spring 15 is stressed in torsion. A close clearance is provided between lugs 13 and 14, to prevent disengagement of the spring ends 15a and 15b when the chair is deflected through large angles from its center position.

When it is desired to turn the seat-and-back unit 2 on the base 1, the lug 14 moves with the seat-and-back unit and carries with it one of the ends 15a or =15b, depending upon the direction in which it is moved from the aligned positon shown in FIG. 3. The other one of the spring ends 15a and 15b remains in engagement with the opposite side of the lug 13. The spring 15 is thereby further stressed in torsion. When the seat-and-back unit 2 is released after having been deflected from its normal position, the spring 15 centers it by carrying the lug 14 back into alignment with the lug 13.

When assembling the swivel mechanism shown, the radial bearing member -10 is first fixed in place in the pedestal. The spring 15 is then inserted, the spring being stressed so that the ends 15a and 15b cross over each other and abut the opposite sides of the lug 13. The chair shell 2, the washer 9, the radial bearing member 4, tube 5 and thrust bearing 6 are assembled separately by the use of the through bolt 7 and head member 8. The stationary thrust bearing member 11 is assembled with the rotatable thrust bearing member 6 before the flange 11b is turned over. The complete seat and base assembly is then inverted, and the screw 12 inserted to hold the thrust bearing member 11 in place and thereby to keep the chair together. If the clearance between the flat portion 2a of the seat shell and the top of the column 1 is not sufiicient, one or more spacer washers may be inserted between the thrust bearing member 11 and the pedestal portion 1a. Standard countersunk washers are suitable.

While I have shown and described a preferred embodiment of my invention, other modifications thereof will readily occur to those skilled in the art, and I therefore intend my invention to be limited only by the appended claims.

I claim:

1. A swivel chair which comprises a pedestal having a wall extending about the vertical axis of the pedestal and defining a hollow space within said pedestal, said hollow space extending from a narrow neck portion at an intermediate elevation in the height of the pedestal to a portion of substantially larger diameter at the upper end of the pedestal, a radial bearing member of annular form about said axis of the pedestal and supported adjacent its lower end by the upper portion of said wall of larger diameter in fixed relation thereto so as to leave a substantial space between said wall and said bearing member outwardly thereof, said bearing member providing an inner radial bearing surface extending about the vertical axis of the pedestal and adjacent said wall within said enlarged space of the pedestal, a thrust bearing member supported by and in fixed relation to said wall of said pedestal within said narrow neck portion of said space and providing a thrust receiving surface of substantial extent about and transversely of the vertical axis, a vertical shaft rotatable on said axis and disposed within said pedestal space and extending between said narrow neck portion and said enlarged upper portion of said space, a rotatable radial bearing member having a portion supported on and extending outwardly from and transversely of said shaft adjacent the upper end of the shaft for rotation therewith and having an outer portion rigidly connected to said outwardly extending portion and providing an outer radial bearing surface extending about said axis and engaging said inner surface of said fixed radial bearing member for transmitting radially directed forces to said fixed radial bearing member, a rotatable thrust member supported on said shaft for rotation therewith and engaging said thrust receiving surface of said fixed thrust bearing member for transmitting thereto downward thrust transmitted to said shaft, a seat disposed above and adjacent the upper end of the pedestal, and means connecting said seat to said shaft for rotation of said seat with said shaft and for transmitting the thrust of said seat and the load thereon to said fixed thrust bearing member through said shaft concomitantly with rotation of said shaft with respect to said fixed bearing members upon rotation of said seat.

2. A swivel chair as defined in claim 1 which comprises means disposed in said enlarged hollow space of said pedestal outwardly of said rotatable radial bearing member and connected to said pedestal at its upper end and connected to said rotatable radial bearing member for biasing said rotatable radial bearing member and said seat and said shaft connected thereto as an assembly to rotate to a given position relative to said pedestal upon rotational movement of said assembly from said given position.

3. A swivel chair as defined in claim 1 in which said pedestal wall at said neck portion provides on an inwardly extending part thereof a surface extending transverse to the axis of the shaft inwardly from said pedestal wall, said thrust bearing member providing a complementary surface for engagement with said transversely extending surface of said pedestal wall, and a screw extending vertically and engaging said inwardly projecting part of said wall and threadedly engaging said fixed thrust bearing member to hold said complementary surface thereof in engagement with said transversely extending surface of said wall.

4. A swivel chair which comprises a pedestal having a wall extending about a hollow space within the pedestal, said hollow space flaring from a narrow neck portion at an intermediate elevation in the height of the pedestal to a portion of substantially larger diameter at the upper end of the pedestal, a radial bearing member supported by said pedestal wall at the inner side thereof in fixed relation thereto within the enlarged hollow space of said pedestal adjacent the upper end thereof, a thrust bearing member supported by and in fixed relation to said pedestal within said neck portion of said space, a rotatable vertical shaft disposed within said pedestal space and extending between said neck portion and said enlarged upper portion of said space, said shaft having a diameter adjacent said neck portion less than but of the degree of the internal diameter of said neck portion of said pedestal, a rotatable radial bearing member carried by said shaft adjacent its upper end for rotation therewith and providing a cylindrical exterior bearing surface having a diameter substantially larger than said shaft and engaging a cylindrical interior surface of said fixed radial bearing, a rotatable thrust bearing member carried by said shaft adjacent its lower end and engaging said fixed thrust bearing member for transmitting to said fixed thrust bearing member the downward thrust transmitted to said shaft, a seat disposed above and adjacent the upper end of said pedestal, means connecting said seat to said shaft for rotation of said seat with said shaft and for transmitting the thrust of said seat and the load thereon through said shaft to said fixed thrust bearing member concomitantly with rotation of said seat upon rotation of said shaft with respect to said bearing members.

5. A swivel chair which comprises a pedestal having a wall extending about a hollow space within said pedestal, said hollow space extending from a narrow neck portion at an intermediate elevation in the height of the pedestal to a portion of substantially larger diameter at the upper end of the pedestal, a radial bearing member supported by and in fixed relation to said pedestal within the enlarged space of said pedestal adjacent the upper end thereof, a thrust bearing member supported by and in fixed relation to said wall of said pedestal within said narrow neck portion of said space and providing a thrust receiving surface of substantial extent about and transversely of the vertical axis of the pedestal, a vertical shaft rotatable on said axis and disposed within said pedestal space and extending between said neck portion and said enlarged upper portion of said space, a rotatable bearing member supported on said shaft adjacent its upper end for rotation therewith and engaging said fixed radial bearing member for transmitting radially directed forces to said fixed radial bearing member, a rotatable thrust bearing member supported on said shaft for rotation therewith and engaging said thrust receiving surface of said fixed thrust bearing member for transmitting thereto downward thrust transmitted to said shaft, a seat disposed above and adjacent the upper end of said pedestal, means connecting said seat to said shaft for rotation of said seat with said shaft and for transmitting the thrust of said seat and the load thereon to said fixed thrust bearing member through said shaft concomitantly with rotation of said shaft with respect to said fixed bearing members upon rotation of said seat, said fixed radial bearing member comprising an outer vertical cylindrical sleeve having at its lower end a horizontally outwardly projecting flange fixed to the pedestal, said rotatable radial bearing member comprising also an inner vertical cylindrical sleeve rotatably fitting within the outer sleeve and having at its upper end a horizontally outwardly projecting flange fixed to the seat, an inwardly projecting lug fixed to said pedestal, said inner sleeve flange carrying a lug projecting downwardly therefrom and spaced radially inwardly from said pedestal lug in a given position of said assembly, and a coil spring encircling said sleeves and having crossed end portions yieldably engaging opposite sides of said lugs and tending to hold said lugs in alignment in said given position and effective to return said assembly to said given position upon rotation of said assembly therefrom.

6. A swivel chair which comprises a pedestal having a wall extending about a hollow space within said pedestal, said hollow space extending from a narrow neck portion at an intermediate elevation in the height of the pedestal to a portion of substantially larger diameter at the upper end of the pedestal, a radial bearing member supported by and in fixed relation to said pedestal within the enlarged space of said pedestal adjacent the upper end thereof, a thrust bearing member supported by and in fixed relation to said wall of said pedestal within said narrow neck portion of said space and providing a thrust receiving surface of substantial extent about and transversely of the vertical axis of the pedestal, a vertical shaft rotatable on said axis and disposed within said pedestal space and extending between said neck portion and said enlarged upper portion of said space, a rotatable bearing member supported on said shaft adjacent its upper end for rotation therewith and engaging said fixed radial hearing member for transmitting radially directed forces to said fixed radial bearing member, a rotatable thrust bearing member supported on said shaft for rotation therewith and engaging said thrust receiving surface of said fixed thrust bearing member for transmitting thereto downward thrust transmitted to said shaft, a seat disposed above and adjacent the upper end of said pedestal, means connecting said seat to Said shaft for rotation of said seat with said shaft and for transmitting the thrust of said seat and the load thereon to said fixed thrust bearing member through said shaft concomitantly with rotation of said shaft with respect to said fixed bearing members upon rotation of said seat, said seat comprising a shell having a flat horizontal under surface provided with an opening therein at its center, said rotatable radial bearing member comprising a vertical cylindrical sleeve having at its upper end a horizontally outwardly projecting flange abutting against the under surface of said shell, said sleeve being axially aligned with said opening of said shell, said shaft comprising a tube axially aligned with and attached to said sleeve and projecting downwardly therefrom, said rotatable thrust bearing member being secured to the lower end of said tube, a convex spring Washer disposed at the upper side of said seat shell with the convex side upward and having an aperture aligned with said shell opening, and a through bolt having a head engaging said convex spring washer and a shank extending downwardly through the aperture and the opening and through the sleeve and the tube and threadedly engaging said rotatable thrust bearing member, said through bolt being effective to hold the rotatable members, the seat and the tube assembled.

References Cited in the file of this patent UNITED STATES PATENTS 412,513 Kramer et al. Oct. 8, 1889 1,532,354 Walton Apr. 7, 1925 1,578,784 Walton Mar. 30, 1926 1,848,183 Madsen Mar. 8, 1932 1,897,676 Ries Feb. 14, 1933 1,942,033 Madsen Jan. 2, 1934 2,217,943 Carlson Oct. 15, 1940 2,329,697 Davies Sept. 21, 1943 2,351,194 Davies June 13, 1944 2,615,766 Wallace Oct. 28, 1952 2,618,315 Scott Nov. 18, 1952 2,664,142 Scheuerman Dec. 29, 1953 2,939,514 Buettner et a1 June 7, 1960 FOREIGN PATENTS 300,299 Switzerland July 31, 1954 531,023 Great Britain Dec. 27, 1940 78 03 Gr at r a Sept 1 5.1

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,055,628 September 25, 1962 Robert H; Savage It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below. 1

Column 2, line. 33', ior "is" read me its column 4 llilfi 67, after "said second occurrence,

insert fixed u Signed and sealed this 7th day of May 1963.

(SEAL) Attest:

Commissioner of Patents 

